J.P. Morgan has filed living wills over the past three years and the Fed has not rejected any of them, Warren said.

“Can you honestly say that J.P. Morgan can be resolved in a rapid and orderly fashion as described in its plans with no threats to the economy and no need for a taxpayer bailout?” Warren asked Yellen.

The Fed chairwoman said she thought the living-will process was meant to be “iterative” and the central bank is working to give the firms “a road-map for where we see obstacles to orderly resolution under the bankruptcy code and to give them an opportunity to address those obstacles.”

“These are extremely complex documents,” with some plans running into tens of thousands of pages, Yellen said.

Warren noted that the Fed has only released 35 pages of information about the J.P. Morgan living will to the public.

She added that the Fed has tools to use if the plans are not credible, including forcing the banks to simplify their structures or forcing them to liquidate some of their assets.